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Phytoplankton and phytobenthos as biological quality elements along karstic river 1* 1 1 1 1 Mejdandžiæ, Maja , Maleševiæ, Nikola , Nemet, Mateja , Kralj Borojeviæ, Koraljka , & Gligora Udoviè, Marija 1 University of Zagreb, Faculty of Science, Department of Biology, Roosevetov trg 6, 10000 Zagreb, Croatia( * [email protected]) INTRODUCTION & AIMS Phytoplankton (potamoplankton), same as phytobenthos, is important biological element required for monitoring in rivers. One of methods in ecology and river quality management is method of grouping phytoplankton in functional groups (FG) and their comparison. The main objectives of this study are to provide longitudinal description of potamoplankton functional groups and comparison with benthic diatom composition along karstic river Lika on two instances. Actual estimation of ecological status of the river is based on phytoplankton Qr index and benthic Croatian Trophic Diatom Index. Additionally, special attention was paid to the diatoms in the plankton and benthos which represent to specific descriptors of this particular karstic ecosystem. The River Lika is the largest underground river in Croatia with a length of 78 km. In the canyon of River Lika (Lika Field) is the reservoir dam Krušèica. Along the river Lika is well known cave park Grabovaèa. We investigated area of the River Lika – reservoir dam Krušèica with upper and downstream sections and one tributary (stream Bakovac). Sampling of potamoplankton and phytobenthos was conducted at seven main points and additionally two secondary points for phytobenthos during May and August 2014. P1 August 2014 P1 May 2014 P2 August 2014 P3 May 2014 P3 August 2014 P4 August 2014 P5 August 2014 P6 May 2014 P6 August 2014 P7 May 2014 P7 August 2014 P4 May 2014 P2 May 2014 P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P3 P4 P5 P7 P7 P1 P2 P3 P4 P5 P7 P7 P9 PC Sampling points 0 10 20 30 40 Number of species May phytoplankton August phytoplankton May benthos August benthos P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P3 P4 P5 P7 P7 P1 P2 P3 P4 P5 P7 P7 P9 PC Sampling points 0 1 2 3 Qr index May phytoplankton August phytoplankton May benthos August benthos 1 2 3 Croatian Trophic Diatom Index P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P3 P4 P5 P7 P7 P1 P2 P3 P4 P5 P7 P7 P9 PC Sampling points 0.5 1 1.5 2 2.5 3 Shannon-Wiener index May phytoplankton August phytoplankton May benthos August benthos P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P4 P5 P6 P7 P1 P2 P3 P3 P4 P5 P7 P7 P1 P2 P3 P4 P5 P7 P7 P9 PC Sampling points 0 0.5 1 Evenness May phytoplankton August phytoplankton May benthos August benthos th 9 Central European Diatom Meeting th th Bremerhaven, Germany, 10 - 14 March 2015 Fig. 1. Light micrographs of dominant species according to seven main sampling points: A - Achnanthidium minutissimum (Kützing) Czarnecki; B - Diatoma ehrenbergii Kützing 1844; C - Encyonopsis cesatii (Rabenhorst) Krammer; D - Encyonopsis microcephala (Grunow) Krammer; E - Fragilaria capucina Desmazieres; F - Navicula antonii Lange-Bertalot. Fig. 2. Number of species for phytoplankton and phytobenthos samples according to sampling sites. Fig. 3. Qr and Croatian Trophic Diatom index for phytoplankton and phytobenthos samples respectivey according to sampling sites. Fig. 5. Evenness values for phytoplankton and phytobenthos samples according to sampling sites. Fig. 4. Shannon-Wiener index for phytoplankton and phytobenthos samples according to sampling sites. RESULTS A total of 45 species contributed more than 2% to the total phytoplankton biomass and presented 17 FG. A total of 122 species was recorded in benthic samples. The most frequent species were Achnanthidium minutissimum (Kützing) Czarnecki , Diatoma ehrenbergii Kützing, Encyonopsis cesatii (Rabenhorst) Krammer, Encyonopsis microcephala (Grunow) Krammer, Fragilaria capucina Desmazieres and Navicula antonii Lange-Bertalot (Fig. 1.) . As expected, benthic samples showed a greater number of species, and further, benthic samples in May showed a greater number of species compared to August (Fig. 2 ) . In May, Qr index showed smaller variation in values (0.37 - 0.69), while in August varied from. 0.30 - 0.75. Croatian Trophic Diatom Index was in the range from 1.7 to 2.5 indicating good to moderate conditions (Fig. 3 ) . Shannon-Wiener diversity index for phytoplankton samples varied from 0.55 - 2.30 in sample from P5 (upperstream area) and P2 (downstream area) collected in May, respectively (Fig 4 ) . Benthic samples showed variations from 0.69 - 2.39 from P3 (epipelon) and P3 (epiphyton) collected in May, respectively (Fig. 4 ) . Evenness (range 0 - 1) for phytoplankton samples showed variations from 0.18 - 0.86 for P5 and P1 collected in May, respectively which is supported by dominance of diatom Navicula spp. in P1 sample (Fig. 5 ) . Evenness for benthic samples varied from 0.35 - 1.0 for P1 (epilithon) and P3 (epipelon) respectively, indicating dominance of two species in P3 sample: Encyonopsis cesatii and Fragilaria capucina (Fig. 5 ) . As expected, Croatian Trophic Diatom Index generated acceptable values for investigated area owing to fact it is developed on Croatian species and data. Disagreements of Qr index and Croatian Trophic Index highlighted the need to normalise the assessment values. ACKNOWLEDGMENTS Authors want to thank Biology Student Association (BIUS) for supporting field surveys which granted this publication. This work has been supported in part by Croatian Science Foundation under the project 6433 and by Ministry of Science under the project No. 119-0000000-1229. M. M. has been supported by University of Zagreb staff exchange mobility grant. Bakovac Lika Lika Reservoir dam ½Krušèica½ P5 May 2014 N
